Study

Red squirrels (Sciurus vulgaris) released in conifer woodland: the effects of source habitat, predation and interactions with grey squirrels (Sciurus carolinensis)

  • Published source details Kenward R.E. & Hodder K.H. (1998) Red squirrels (Sciurus vulgaris) released in conifer woodland: the effects of source habitat, predation and interactions with grey squirrels (Sciurus carolinensis). Journal of Zoology, 244, 23-32

Actions

This study is summarised as evidence for the following.

Action Category

Release translocated/captive-bred mammals into area with artificial refuges/breeding sites

Action Link
Terrestrial Mammal Conservation

Provide supplementary food during/after release of translocated mammals

Action Link
Terrestrial Mammal Conservation

Use holding pens at release site prior to release of translocated mammals

Action Link
Terrestrial Mammal Conservation
  1. Release translocated/captive-bred mammals into area with artificial refuges/breeding sites

    A study in 1993–1994 on a forested peninsula in Dorset, UK (Kenward & Hodder 1998) found that none of the translocated red squirrels Sciurus vulgaris provided with nest boxes, supplementary food and water (in and once released from pre-release pens) survived over five months after release. Out of 14 translocated red squirrels, 11 (79%) survived over one week, three (21%) survived >3 months and none survived >4.5 months. At least half of the 14 squirrels were killed by mammalian predators. Intact carcasses that were examined showed signs of weightloss and stress (see original paper for details). Between October and November 1993, fourteen wild-born red squirrels were released into an 80-ha forest dominated by Scots pine Pinus sylvestris. The forest had no red squirrels but had introduced grey squirrels Sciurus carolinensis. Capture and release sites were similar habitats. Squirrels were transported in wooden nest boxes filled with dry hay. Squirrels were placed with their nest boxes into 1.5 × 1.5 × 1.5 m weldmesh pens surrounded by electric fencing for 3–6 days before release. Squirrels were kept individually except for 2 males who shared a pen. Supplementary food comprised a mixture of seeds, nuts and fruit on trays and in feed hoppers. After release, squirrels continued to have access to food, water and nest boxes inside the pens and outside (20-100 m away). All squirrels were radio-tagged and located 1–3 times/day, for 10–20 days after release and thereafter every 1–2 days.

    (Summarised by: Ricardo Rocha)

  2. Provide supplementary food during/after release of translocated mammals

    A study in 1993–1994 on a forested peninsula in Dorset, UK (Kenward & Hodder 1998) found that none of the translocated red squirrels Sciurus vulgaris provided with supplementary food and water in holding pens (with nestboxes) and once released survived over five months after release. Out of 14 translocated red squirrels, 11 (79%) survived over one week. Only three (21%) survived >3 months and none survived >4.5 months. At least half of the 14 squirrels were killed by mammalian predators. Intact carcasses examined showed signs of weight loss and stress (see original paper for details). Between October and November 1993, fourteen wild-born red squirrels were released into an 80-ha forest dominated by Scots pine Pinus sylvestris. The forest had no red squirrels but had introduced grey squirrels Sciurus carolinensis. Capture and release sites were similar habitats. Supplementary food comprised a mixture of seeds, nuts and fruit on trays and in feed hoppers. Squirrels were kept in 1.5 × 1.5 × 1.5 m weldmesh pens surrounded by electric fencing for 3–6 days before release. Squirrels were kept individually except for 2 males who shared a pen. After release, squirrels continued to have access to food, water and nest boxes inside the pens and outside (20-100 m away). All squirrels were radio-tagged and located 1–3 times/day, for 10–20 days after release and thereafter every 1–2 days.

    (Summarised by: Ricardo Rocha)

  3. Use holding pens at release site prior to release of translocated mammals

    A study in 1993–1994 on a forested peninsula in Dorset, UK (Kenward & Hodder 1998) found that none of the translocated red squirrels Sciurus vulgaris released into holding pens (with supplementary food, water and nestboxes) survived over five months after release. Out of 14 translocated red squirrels, 11 (79%) survived over one week. Only three (21%) survived >3 months and none survived >4.5 months. At least half of the 14 squirrels were killed by mammalian predators. When intact carcasses were examined they showed signs of weight loss and stress (see original paper for details). Between October and November 1993, fourteen wild-born red squirrels were released into an 80-ha forest dominated by Scots pine Pinus sylvestris. The forest had no red squirrels but had introduced grey squirrels Sciurus carolinensis. Capture and release sites were similar habitats. Squirrels were kept in 1.5 × 1.5 × 1.5 m weldmesh pens surrounded by electric fencing for 3–6 days before release. Squirrels were kept individually except for two males who shared a pen. After release, squirrels continued to have access to food, water and nest boxes inside the pens and outside (20-100 m away). All squirrels were radio-tagged and located 1–3 times/day, for 10–20 days after release and thereafter every 1–2 days.

    (Summarised by: Ricardo Rocha)

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